(a) Field of the Invention
The present invention relates to a plasma display panel (PDP), and more particularly, to a plasma display panel in which the formation of discharge sustain electrodes is improved to thereby enhance discharge efficiency.
(b) Description of the Related Art
A PDP is a display device that uses vacuum ultraviolet rays generated by gas discharge in discharge cells to excite phosphors, thereby realizing the display of images. With its ability to realize high-resolution images, the PDP is emerging as one of the most popular flat panel display configurations used for wall-mounted televisions and other similar large-screen applications. The different types of PDPs include the AC-PDP, DC-PDP, and the hybrid PDP. The AC PDP utilizing a triode surface discharge structure is becoming the most common configuration.
In the AC PDP with a triode surface discharge structure, address electrodes, barrier ribs, and phosphor layers are formed on a rear substrate corresponding to each discharge cell. Discharge sustain electrodes including scan electrodes and display electrodes are formed on a front substrate. A dielectric layer is formed covering the address electrodes on the rear substrate, and, similarly, a dielectric layer is formed covering the discharge sustain electrodes on the front substrate. Also, discharge gas (typically an Ne—Xe compound gas) is filled in the discharge cells.
Using the above structure, an address voltage Va is applied between an address electrode and a scan electrode to select a discharge cell. Next, a discharge sustain voltage Vs of 150-200V is applied between the display electrode and the scan electrode of the selected discharge cell such that discharge gas effects plasma discharge, and vacuum ultraviolet rays having wavelengths of 147 nm, 150 nm, and 173 nm are emitted from the excited Xe atoms made during plasma discharge. The vacuum ultraviolet rays excite phosphors so that they glow (i.e., emit visible light) and thereby enable color display.
In the PDP operating in this manner, the shape of the discharge sustain electrodes greatly affects sustain discharge characteristics. The first discharge sustain electrodes (i.e., scan electrodes and display electrodes) were transparent electrodes mounted substantially perpendicular to the address electrodes. Further, bus electrodes made of metal were formed on the transparent electrodes to provide a certain degree of conductivity to the transparent electrodes.
However, the discharge sustain electrodes structured as described above are not made with the goal of optimizing discharge characteristics between discharge cells. Also, since the spaces between the transparent electrodes are large, a significant voltage is required. Accordingly, there have been efforts to improve the formation of discharge sustain electrodes to overcome these problems.
U.S. Pat. No. 5,640,068 discloses discharge sustain electrodes in which areas of stripe transparent electrodes opposing barrier ribs are reduced in width. Also, U.S. Pat. No. 5,661,500 discloses discharge sustain electrodes formed using transparent electrodes that protrude into areas of discharge cells from bus electrodes. U.S. Pat. No. 6,288,488 discloses discharge sustain electrodes formed using transparent electrodes that protrude into areas of discharge cells in a “T” configuration from bus electrodes.
However, in all of these patents, pairs of transparent electrodes are provided opposing one another (on the same plane) at a predetermined distance. As a result, when a sustain voltage is applied between the scan electrodes and display electrodes during a sustain interval, plasma discharge starts in the discharge gap between these electrodes, after which the plasma discharge spreads to edges of the discharge cells in roughly an arc configuration.
Such dispersion of plasma discharge causes differences in brightness in even a single discharge cell. That is, following address discharge, during plasma discharge by the collision of electrons (−) accumulated on the display electrodes with ions (+) accumulated on the scan electrodes, the brightest light is generated at the center of the discharge gap between the scan electrodes and display electrodes, then bright light is generated at the scan electrodes, and then at the display electrodes. As a result, non-uniform brightness characteristics result in each of the discharge cells.
Further, in the above patents, although the discharge sustain electrodes include transparent electrodes opposing one another in each of the discharge cells, there are still areas of the transparent electrodes that exist in locations uninvolved with discharging. This increases the amount of power consumed as a result of the relatively large area covered by the transparent electrodes. Also, plasma discharge generated in the discharge cells diffuses to the barrier ribs through the transparent electrodes to thereby reduce discharge efficiency.